1. Field of the Invention
The present invention deals with the field of devices wherein various different kinds of parts are tested for unwanted leakage. Parts that are tested in this manner are used in all areas of industry but examples of such items which require testing for leaks include gas masks, automotive brake lines, automotive fuel lines, gas tanks, gas tank filler lines, air conditioning lines and other connecting lines or conduits usually, but not always, made of metallic or elastomeric materials.
Normally a part to be tested such as a fuel line is sealed by plugging each opposite end while allowing a fill line and a pressure sensing member to be positioned within one of the plug components such as to be in fluid flow communication with the sealed chamber defined within the line or conduit. Normally the test part is then filled with a precise amount of gas such as air under pressure up to a predetermined test pressure value. This test pressure value is usually greater than atmospheric pressure but the present invention is certainly usable to test for leakage at less than atmospheric pressure, more commonly referred to as vacuum leak testing. Then, after a short period of pressure and temperature stabilizing time, the pressure monitored by the sensing means is compared with a predetermined threshold level and in this manner any leaks can be detected.
Such apparatus is normally heavily dependent upon the pre-set value of a coarse pressure valve or pressure control device and, thus, a fairly large loss of pressure from the approximate value to which the coarse device is set is required in order to determine if a an excessive amount of leakage has occurred. The present invention provides a unique method which includes a snapshot instantaneous pressure measurement performed immediately after temperature and pressure stabilization of the initial pressurization of a part which can be utilized in coordination with a calculation process to determine whether a part is good or bad after only very small pressure losses over relatively small time periods. Also the present invention provides a unique method for assuring proper full pressurization with a coordinated error detecting and displaying process.
This method disclosed herein is useful for pressure testing for leakage at pressures greater than standard atmospheric pressure and, also, is usable for vacuum testing for leakage at pressures less than standard atmospheric pressure. Normally one standard atmospheric pressure is approximately 14.7 pounds per square inch. This value will vary at different locations depending upon many different factors such as elevation and temperature. It is important to appreciate that all pressure values herein are presented in absolute value terms. As such, a pressure of approximately 29.4 psi should be interpreted to mean pressurizing to about double the standard atmospheric pressure. On the other hand pressures listed below about 14.7 psi such as 5 or 10 psi should be considered as an environment subject to at least a partial vacuum. Thusly, any reference to a pressurization of zero psi is a reference to a theoretical perfect vacuum.
2. Description of the Prior Art
Various patents have been granted for leak testing or testing of parts for leaks such as U.S. Pat. No. 4,089,208 patented May 16, 1978 to N. J. Franks et al and assigned to Owens-Illinois, Inc. on a “Pressure Test Fixture For Pressurized Containers”; and U.S. Pat. No. 4,106,263 patented Aug. 15, 1978 to W. A. Conrad and assigned to Rheem Manufacturing Company on an “Apparatus For Pressure Testing Of Containers”; and U.S. Pat. No. 4,126,034 patented Nov. 21, 1978 to W. A. Conrad and assigned to Rheem Manufacturing Company on a “Method And Apparatus For Container Pressure Testing”; and U.S. Pat. No. 4,182,159 patented Jan. 8, 1980 to R. K. Churchman and assigned to Otis Engineering Corporation on a “Pressure Testing Tool”; and U.S. Pat. No. 4,197,733 patented Apr. 15, 1980 to R. W. Holland on a “Pressure Test Apparatus”; and U.S. Pat. No. 4,207,146 patented Jun. 10, 1980 to S. Kunke and assigned to Dragerwerk Aktiengesellschaft on a “Process For Testing Gases In Body Fluids For Partial Pressure And To A Testing Device Therefor”; and U.S. Pat. No. 4,291,573 patented Sep. 29, 1981 to S. J. Richter et al and assigned to The Coca-Cola Company on a “Reject System For In-Line Pressure Testing Systems”; and U.S. Pat. No. 4,366,715 patented Jan. 4, 1983 to J. H. Bradshaw and assigned to The Gillette Company on a “Pressure Testing Apparatus”; and U.S. Pat. No. 4,378,692 patented Apr. 5, 1983 to L. I. Walle and assigned to Air Monitor Co., Inc. on a “Leak Detecting Monitor”; and U.S. Pat. No. 4,413,501 patented Nov. 8, 1983 to P. Schrock on an “Apparatus For Pressure Testing Tubing”; and U.S. Pat. No. 4,417,465 patented Nov. 29, 1983 to R. R. Noe et al on a “Portable Test Unit, For High Pressure Testing Of Tubes”; and U.S. Pat. No. 4,494,402 patented Jan. 22, 1985 to P. T. Carney on a “Device And Method For Pressure Testing”; and U.S. Pat. No. 4,555,935 patented Dec. 3, 1985 to K. Elert and assigned to The Stroh Brewery Company on an “Apparatus For Pressure Testing of Can Bodies And Lids”; and U.S. Pat. No. 4,581,919 patented Apr. 15, 1986 to M. M. Sullivan on a “Retrievable Hydrostatic Testing Tool For Pressure Testing Tubing”; and U.S. Pat. No. 4,587,619 patented May 6, 1986 to V. G. Converse, III et al and assigned to Scans Associates, Inc. on a “Method And Apparatus For Electronic Leak Testing”; and U.S. Pat. No. 4,617,824 patented Oct. 21, 1986 to L. P. Cybulski et al and assigned to R. R. McGlogan Equipment Ltd. on a “Cylinder Head Pressure Testing Apparatus”; and U.S. Pat. No. 4,675,070 patented Jun. 23, 1987 to M. Pasternicki and assigned to Sidel on a “Machine For Pressure Testing And Bottom Capping Plastic Bottles”; and U.S. Pat. No. 4,715,214 patented Dec. 29, 1987 to R. S. Tveter et al and assigned to S. Himmelstein and Company on a “Leak Tester”; and U.S. Design Pat. No. Des.294,229 patented Feb. 16, 1988 to P. Bonazzi on a “Machine For Pressure Testing Truck Tires”; and U.S. Pat. No. 4,791,805 patented Dec. 20, 1988 to D. C. Gates and assigned to Expertek, Inc. on a “Fuel Tank Leak Detection Apparatus”; and U.S. Pat. No. 4,942,758 patented Jul. 24, 1990 to D. H. Cofield on a “High Speed Leak Tester”; and U.S. Pat. No. 4,953,396 patented Sep. 4, 1990 to J. W. Langsdorf et al and assigned to General Mills, Inc. on a “Leak Detector For Containers”; and U.S. Pat. No. 5,092,162 patented Mar. 3, 1992 to F. Self on a “Static Pressure Testing Apparatus”; and U.S. Pat. No. 5,187,974 patented Feb. 23, 1993 to K. E. Mellits et al and assigned to Snap-On Tools Corporation on a “Vehicular Pressure-Testing Apparatus”; and U.S. Pat. No. 5,201,212 patented Apr. 13, 1993 to B. N. Williams and assigned to Tanknology Corporation International on a “Line Leak Detector And Method”; and U.S. Pat. No. 5,216,914 patented Jun. 8, 1993 to J. R. Horner and assigned to Horner Creative Products, Inc. on “Methods And Systems For The Negative Pressure Testing Of Underground Storage Tanks Containing Highly Vaporous Hydrocarbon Liquids”; and U.S. Pat. No. 5,317,899 patented Jun. 7, 1994 to R. J. Hutchinson et al and assigned to Control Engineers, Inc. on a “Method For Detecting Leaks In Underground Product Lines”; and U.S. Pat. No. 5,331,842 patented Jul. 26, 1994 to R. G. Wellemeyer and assigned to Smith Fiberglass Products Inc. on a “Cyclical Pressure Testing Apparatus”; and U.S. Pat. No. 5,375,455 patented Dec. 27, 1994 to J. W. Maresca, Jr. et al and assigned to Vista Research, Inc. on “Methods For Measuring Flow Rates To Detect Leaks”; and U.S. Pat. No. 5,377,530 patented Jan. 3, 1995 to B. F. Allen et al and assigned to Combustion Engineering, Inc. on “Apparatus For Hydrostatic Pressure Testing Of Tubular Products”; and U.S. Pat. No. 5,412,978 patented May 9, 1995 to G. R. Boone and assigned to Phase 1 Instruments, Inc. on a “Leak Detection System”; and U.S. Pat. No. 5,415,033 patented May 16, 1995 to J. W. Naresca, Jr. et al and assigned to Vista Research, Inc. on a “Simplified Apparatus For Detection Of Leaks In Pressurized Pipelines”; and U.S. Pat. No. 5,528,926 patented Jun. 25, 1996 to J. P. Emmitte, Jr. on a “Method For Pressure Testing Valves”; and U.S. Pat. No. 5,546,789 patented Aug. 20, 1996 to D. J. Balke et al and assigned to InterTech Development Company on a “Leakage Detection System”; and U.S. Pat. No. 5,563,336 patented Oct. 8, 1996 to R. J. Mallet on an “Apparatus For Pressure Testing Of Tubulars”; and U.S. Pat. No. 5,574,213 patented to A. W. Shanley on Nov. 12, 1996 on an “Apparatus And Method For Detecting Leaks”; and U.S. Pat. No. 5,616,854 patented Apr. 1, 1997 to P. Berg on an “Apparatus For Pneumatically Testing Pipes For Leaks”; and U.S. Pat. No. 5,760,296 patented Jun. 2, 1998 to M. S. Wilson and assigned to ABW Australia Pty. Ltd. on a “Cooling System Pressure Testing For Leak Detection”; and U.S. Pat. No. 5,847,264 patented Dec. 8, 1998 to C. R. Martin et al and assigned to Roper Holdings, Inc. on a “Leak Tester With Flexible Equation Capabilities”; and U.S. Pat. No. 5,880,358 patented Mar. 9, 1999 to J. P. Emmitte, Jr. on a “Method And Apparatus For Pressure Testing Valves”; and U.S. Pat. No. 5,883,302 patented Mar. 16, 1999 to L. R. Kent and assigned to Kent & Swart Investments CC on “Pressure Testing Of Engine Components Having Coolant Flow Paths”; and U.S. Pat. No. 5,920,009 patented Jul. 6, 1999 to T. Enders et al and assigned to Robert Bosch GmbH on a “Method For Generating A Certain Constant Pressure In A Test Liquid Of A Test Apparatus”; and U.S. Pat. No. 6,116,340 patented Sep. 12, 2000 to S. J. Wilson et al and assigned to Atlantic Richfield Company on a “Downhole Build-Up Pressure Test Using Coiled Tubing”; and U.S. Pat. No. 6,164,139 patented Dec. 26, 2000 to P. P. Krimmer on a “Pressure Test Gauge Assembly”; and U.S. Pat. No. 6,199,432 patented Mar. 13, 2001 to D. Dunn and assigned to BG PLC on “Fluid Pressure Testing”; and U.S. Pat. No. 6,209,560 patented Apr. 3, 2001 to J. B. Shaw and assigned to Presto-Tap, LLC on a “Pressure Testing Assembly And Testing Method For Propane Tank Systems”; and U.S. Pat. No. 6,223,766 patented May 1, 2001 to J. B. Shaw et al and assigned to Presto-Tap, LLC on a “Pressure Testing Apparatus And Testing Method For Propane Tank Systems” and U.S. Pat. No. 6,279,383 patented Aug. 28, 2001 to D. J. Balke et al and assigned to Intertech Corporation on a “Method And Apparatus For Detecting Leakage”; and U.S. Pat. No. 6,318,155 patented Nov. 20, 2001 to B. Carr on a “Pressure Testing Apparatus”; and U.S. Pat. No. 6,348,869 patented Feb. 19, 2002 to R. P. Ashworth and assigned to Lattice Intellectual Property Limited on a “Pipe Leak Detection”; and U.S. Pat. No. 6,530,264 patented Mar. 11, 2003 to K. K. Rink et al and assigned to Autoliv ASP, Inc. on “Detection Systems And Methods”; and U.S. Pat. No. 6,549,857 patented Apr. 15, 2003 to M. R. Fierro et al and assigned to Vista Research, Inc. on “Methods For Detecting Leaks In Pressurized Piping With A Pressure Measurement System”.